Signal is a privacy-focused encrypted chat solution, but the first thing it wants after you sign up is to access all the contacts on your phone. Here̵
Why does Signal want your contacts?
Signal works based on telephone numbers. You need a phone number to register. That phone number identifies you on Signal. If someone knows your phone number, they can message you on Signal. When you message someone on Signal, they see your phone number.
You cannot use Signal without revealing your phone number to the people you contact. In other words, your Signal address is your phone number. (The only way to get around this is to sign up with a secondary phone number, which people will see instead.)
Like other modern chat applications, Signal requests access to your iPhone or Android phone’s contacts. Signal uses your contacts to find other people you know who are already using Signal.
You don’t have to ask everyone you know if they use Signal. If a phone number in your contacts is associated with a Signal account, Signal allows you to contact that person. Signal is designed as a user-friendly app that can quickly replace SMS.
What that means is that, with access to your contacts, you’ll see a list of people you know who use Signal when you tap “New Message” in Signal.
Does Signal tell other people when you join?
When you join Signal, other people who have you in their contacts will see a message that you have joined and are now available on Signal.
This message will not be sent from your Signal app and will appear even if you do not allow Signal to access your contacts. Signal wants to let people know that they can now reach you on Signal and not need to use SMS.
To be clear, if someone else has your phone number in their contacts, they’ll get a message that you just joined Signal when your phone number is used to create a Signal account. They see the name they have associated with your phone number in their contacts. That’s all that happens when you join. Signal will not contact anyone in your contacts to let them know that you have signed up.
Does Signal upload your contacts to its servers?
Some chat apps upload your contacts to the service’s servers, store them, and use them to match you with other people you know on that service.
So it’s fair to ask, does Signal upload all of your contacts and store them forever?
No, Signal does not store this information indefinitely. Signal hash phone numbers and regularly sends them to its servers to help everyone discover which of their contacts are using Signal. This is how Signal’s documentation puts it:
Signal periodically sends truncated cryptographically hashed phone numbers for contact tracking purposes. Names are never sent and the information is not stored on the servers. The server responds with the contacts that are Signal users and then immediately deletes this information. Your phone now knows which of your contacts is a Signal user and notifies you if your contact has just started using Signal.
What happens if you don’t give access to contacts?
If you’re not comfortable with this, Signal works without access to your contacts. It just works a little differently – without any of the useful conveniences.
If you don’t give Signal access to your contacts, it won’t know who you know. You have to wait for those people to contact you or use “Find by Phone Number” and type someone’s phone number to contact them.
How do you know if that other person is using Signal? Well, you’ll probably have to ask them through another chat service first. This is why Signal offers contact detection – instead of having a conversation about using Signal on another chat service, you can instantly start talking to someone you know on Signal, even if you had no idea they were before. signed up for Signal.
When you first contact someone, you will only see their phone number. That’s because Signal profiles are encrypted and the key is only shared with your contacts and people you contact. This prevents people from simply determining whose name is associated with a particular phone number by looking it up on Signal.
Signal works best with your contacts
Ultimately, Signal is designed to work best when you give it access to your contacts. It is designed as a drop-in replacement for SMS.
Let’s face it, if you don’t trust Signal to treat your contacts as privately as the documentation promises, then it might not be a good idea to entrust your conversations to Signal.
Of course, you can still use Signal without giving it access to your contacts. That’s your choice, but it will make it more difficult to find and contact people you know on Signal.
You can even change your mind and allow Signal to access your contacts after using it – just go to your smartphone’s settings and allow the app to access your contacts. On an iPhone, go to Settings> Privacy> Contacts or Settings> Signal to do this. On an Android phone, go to Settings> Apps & notifications> Signal> Permissions.